Hydraulic pump



R. E.- M GEE HYDRAULIOPUMP 3 June V15, 1937.

Filed Sept. 12, 1935 7 swig 48 INVENTOR. float/er 5 M5 6::

\ ATTORNEY.

Patented June 15, 1937 UNITED STATES PATENT OFFICE HYDRAULIC PUMJP Robert E. McGee, Beeville, Tex.

Application September 12, 1935, Serial No. 40,208

4 Claims.

This invention relates to new and useful improvements in hydraulic pumps.

One object of the invention is to provide an improved hydraulic pump which may be utilized to actuate a ram, jack, or other mechanism.

An important object of the invention is to provide an improved hydraulic pump which is so constructed that upon initial actuation the pump will act as a large displacement low pressure pump,

further actuation of said pump converting the same into a small displacement high pressure pump, whereby when the load is light a large amount of fluid is displaced at a low pressure and when said load increases a small amount of fluid is. displaced under a high pressure.

Anotherobject of the invention is to provide an improved hydraulic pump which includes a double piston, one larger than the'other, the pistons being so arranged that upon initial actuation of the pump the large piston is moved to displace a greater amount of fluid under a low pressure, continued actuation of the pump causing the smaller piston to come into action to displace less fluid under a high pressure, whereby the pump is automatically converted from a low pressure to a high pressure pump as the load increases and the high pressure is necessary.

A further object of the inventionis to provide an improved hydraulic pump including a large piston and a small piston with means for connecting the two pistons so that they will move simultaneously, so that upon initial actuation of the pump a large amount of fluid under a comparatively low pressure will be displaced, and means for disconnecting the pistons from each other after the large piston has completed its full stroke, whereby the small piston may then be actuated independently of the large piston to displace fluid under a high pressure.

A still further object of the invention is to provide an improved hydraulic pump including a large piston slidable within a cylinder and a small piston slidable within. the large piston with means for connecting the two pistons together so that they will move as a unit, and means actuated by the fluid pressure for disconnecting the two pistons when the fluid pressure has equalled the pressure being exerted thereagainst by the large piston whereby after such equalization the small piston may be independently operated to increase the pressure of the fluid.

A construction designed to carry out the invention will be hereinafter described, together with other featuresof the invention.

The invention will be more readily understood from a reading of the'iollowing specification and by reference to the accompanying drawing, in which an example of the invention is shown, and. wherein:

Figure 1 is an elevation of a hydraulic pump, 5 constructed in accordance with the invention.

Figure 2 is a transverse, vertical sectional view taken on the line 2-2 of Figure 1, and showing both pistons in a lowered position,

Figure 3 is a plan view, 10

Figure 4 is a view similar to Figure 3, and showing the large piston locked in its lowered position,

Figure 5 is an elevation of the upper portion of the pump taken at right angles to Figure 1, and 15 Figure 6 is a transverse, vertical sectional view taken on the line 66 of Figure 3.

In the drawing the numeral l0 designates a cylinder which is shown disposed vertically, and this cylinder has its bottom closed while its upper 20 end is opened. The cylinder may be made of metal, or any other suitable material and its particular size is subject to variation. The upper end of the bore of the cylinder is formed with an internal, annular shoulder H on which a suitable 25 packing ring l2 rests. The packing ring is held in position by a suitable packing gland l3 which is threaded into the upper end of said cylinder,

' as is clearly shown in Figure 6. The packing gland has an annular peripheral flange at its 30 upper end and the upper end of the cylinder is counter sunk at M whereby when the gland is screwed downwardly into position the upper end thereof will be flush with the top of the cylinder.

An enlarged piston I5 is mounted to slide with- 35 in the cylinder l0 and the piston has a length substantially the length of said cylinder. The upper end of said piston is provided with an outwardly directed peripheral flange l6, and this flange is arranged to engage the upper end of the cylin- 4o der when said piston is in its lowermost position (Figure 2) The piston is provided with an axial bore ll which extends throughout the length thereof and the upper end of the bore is formed with an annular shoulder or recess l8 whereby 45 a suitable packing ring l9 and packing gland 69 may be located therein. An inner or reduced piston 20 is mounted to slide within the axial bore ll of the large piston I5 and this inner piston is provided with an enlarged head 20' near its upper 50 end.

When the piston 20 is in its lowermost position within the axial bore ll (Figure 2), the head 20' thereof is located within an upwardly extending collar 2! which is made integral with the enlarged 55 I piston I5. The piston I5 is provided with a suitable packing cup I5, while the smaller piston 20 has a similar packing cup :2 at its lower end. It will be seen by observing Figure 2 that the enlarged piston I5 is arranged to slide within the cylinder I0. Leakage of fluid is prevented by the packing cup I5 and the packing ring I2 at the upper end of the cylinder. Leakage through the bore IT of the large piston is prevented by the packing cup 22 on the inner piston 20 and also by the packing ring I8 at the upper end of said bore.

The bottom I of the cylinder is provided with a port 23 which extends diametrically through said bottom. One end ofthe port has an inlet pipe 24 connected therewith whereby hydraulic fluid is introduced into said port. A suitable check valve 25 is connected in the inlet line 24. The other end of the port has an outlet pipe 26 connected therewith which also has a check valve 21 mounted therein. The port communicates with the interior of the cylinder Ill through an axial opening 28 which is formed in the bottom Ill. Thus it will be seen that hydraulic fluid entering the port through the inlet pipe 24 may flow into the interior of the cylinder I0 when the pistons I and 20 are in their raised position. It

will be obvious that when the pistons move downwardly within the cylinder the hydraulic fluid will be forwarded outwardly through the port 23 into the outlet line 26 and to the check valve 21 and then to a ram, jack, or other mechanism.

For reciprocating the pistons I5 and 20 within the cylinder, the head 20 of the inner piston 20 is provided with an upwardly extending arm 29. This arm has a lever 30 pivoted thereto, as is cleary shown in Figure 1. The pivot of the lever is nearer one end of said lever and that end of the lever is pivoted to an upwardly extending bracket arm 3'I which is preferably made integral with, and extends upwardly from the cylinder I0. It will be seen that when the lever 30 is swung on its pivot the inner piston will be raised and diametrically opposite, outwardly extending pins- 32. These pins are arranged to engage in L-slots 33 which are formed in the collar 2| which extends upwardly from the enlarged piston I5 (Figures 2 and 5). It will be 'seenthat when the pins 32 are engaging in the horizontal leg of the slots 33 that the pistons I5 and 20 are connected together, whereby a vertical movement of the inner piston 20 will move the large piston I5 vertically within the cylinder I0. Therefore, so long as said pins are in engagement with the slots the pistons operate a single unit and pressure is applied to the hydraulic fluid beneath the piston by the enlarged piston I5. It is noted that when the pistons are so connected the inner piston becomes an integral part of the large piston and does not act independently thereof.

' Assuming for purposes of description, that the outlet line 26 has its opposite end connected to a mm (not shown) it will be obvious that when the "lever 30 of the device is swung with the pistons I5 and 20 connected together through the medium pf the pins 32, that the hydraulic fluid beneath ihe-pistons will be forced outwardly to the ram the enlarged piston I5. Due to the large crossthe outlet line 26 will be under a comparatively low pressure. However, at this time a comparatively large amount of fluid will be displaced because of the large size of the piston I5. Therefore so long as the pistons I5 and 20 are connected together and the lever 30 is swung it will be seen that a low pressure large displacement pump will be had. Therefore when the ram is first actuated, at which time the load is light, a comparatively large amount of hydraulic fluid under a low pressure is forced thereagainst. This is desirable because upon initial movement of the ram when the load is light a high pressure fluid is not necessary and by providing a comparatively large amount of fluid under a low pressure the initial movement of the ram is increased. When the back pressure on the fluid Within the line 25 increases due to an increased load on the ram which it is operating, a point will be reached when this back pressure is equal to the pressure which can be exerted downwardly by the enlarged piston I5. When this occurs further actuation of the enlarged piston I5 will be stopped and therefore it is necessary to apply more pressure to the fluid. At such time it is desirable to disconnect the piston I5 from the smaller piston 20 and permit the smaller piston to operate independently of the large piston. Due to the small cross-sectional area of the inner piston 20 it will be seen that a much higher pressure may be applied to the fluid through the reciprocation of this smaller piston. For automatically disconnecting the two pistons from each other when the equalization of pressure, above referred to, occurs, the flange I6 of the large piston I5 is formed with a pair of diametrically opposite notches or cut out portions 35 (Figures 3 and 4). Normally, these notches are in alignment with upwardly extending arms 36 which are formed integral with the cylinder I0. By observing Figure 3, it will be seen that with the notches in alignment with said arms, that the piston I5 is free'to move vertically. The lower end of the arms 36 are provided with inwardly directed slots 0r notches 31 which are of a width substantially equal to the width of the flange I6. Therefore, when the piston I5 is rotated in a clockwise direction (Figure 3) the cut out portions 35 of the flange It will be moved out of alignment with the vertically extending arms 36 and the flange I6 will move into the notches 31 on the inner face of said arm. When the flange engages in these notches (Figure 2) it will be seen that further vertical movement of the piston I5 will be prevented. It is noted that the notches 31 are so located that the piston I5 must be in its lowermost position before the flange I6 can engage said notches. Therefore, the notches 31 and flange I6 provide means for locking the large piston I5 in its lowermost position. It is further pointed out that when the piston I5 is rotated to engage the flange I6 in the notches 31, such rotation causes the collar 2I at the upper end of said piston to be rotated therewith. Rotation of this collar (Figure 5) in a clockwise direction causes the horizontal leg of the L-shaped slots 33 to move away from the pin 32 whereby said pin is aligned with the vertical leg of the slot. Thus it will be seen that rotation of the piston I5 not only looks said piston in its lowermost position, but also causes the pin 32 to be disengaged from the slots 33 whereby the inner or smaller piston 20 is free to move vertically within the axial bore I! of the piston I5.

For automatically accomplishing the rotation of the large piston l to disconnect the inner piston therefrom and also to lock said large piston in its lowermost position, a check valve 40 is provided. The valve 40 is connected in a bypass line 4| which has one end connected with the interior of the cylinder In above the bottom thereof.- The other end of the line 4| is connected to the met line 24 at a point in front of the check valve 40. The valve stem 42 of said valve extends upwardly from the upper end of the valve and a coil spring 43 normally holds said valve close-d. The upper end of the stem on the inner periphery of a metal ring 45 which is slidably mounted on the upper end of the cylinder Ill. The extreme upper end of the rod 44 has an outwardly directed lug 41 which overhangs the upper end of the ring 46. This lug is adapted to flt in a recess or notch 38 which is formed in the upper end of the ring 46. It will be obvious by observing Figures 1 and 2 that when the valve 40 is in a closed position the lug 41 is in engagement with the recess 38-whereby the ring 45 is held in a stationary position with relation to the cylinder ID.

The ring 46 has one end of a coil spring 48 secured thereto. This coil spring is wound around the cylinder l0 and has its other end secured to said cylinder. It'is pointed out that when the spring is first located it is placed under a tension whereby it tends to rotate the ring 48 in a clockwise direction. So long as the lug 4'! of the rod 44 is in engagement with the recess or notch 45' in the upper side of the ring 46,

it will be obvious that said ring is held in its fixed position and is not capable of a rotation. However, when the rod 44 is raised to disengage the lug 47 from the recess 45' it will be obvious that the spring 48 will immediate-1y rotate the ring 46 in a clockwise direction. For communicating this rotatable movement of the ring 46 to the large piston l5, the ring is provided with an upwardly extending rod 50. This rod is so positioned that when the ring is held in its stationary position by the engagement of the lug 41 in the notch .45, said rod 50' is rotated contiguous to a radially extending handle 5| which is made integral with the flange |6 of the piston .|5. By observing Figure 3, it will be see-n that when the lug 41 is disengaged from the not-ch 45' due to.the lifting of the rod 44, the ring 46 will be rotated by the coil spring 48. R0- tation 'of the ring 46 will,of course, move ,the upwardly extending arm 50 around the outer periphery of the cylinder In. The movement of this rod causes said rod to engage the radially extended handle 5| on the piston l5, whereby said piston is rotated in a clockwise direction. As has been explained the clockwise rotation of the piston l5 will cause the flange I6 to engage the notches 31 in the arm 36 to lock the large piston I5 in its lowermost position. At the same time this rotation of the piston l5 causes the pins 32 on the inner or smaller piston 20 to disengage the horizontal leg of the L-slot 33, Where-- by the inner or smaller piston 20 is free to undergo a vertical movement within the axial bore l! of the large piston l5.

In operation, the'parts are moved to the position shown in Figure 1, with the inner or smaller piston 20 connected with the large piston |5 through the medium of the pins 32 and slots 33. Also, the cut out portions 35 of the flange I6 of the large piston are in alignment with the vertical arms 36 which extend upwardly from the cylinder Ill. When the hand lever 30 is depressed it will be obvious that the two pistons will move as a unit. Therefore, as the large piston l5, and the small piston connected therewith, move vertically within the cylinder l0 it will' be obvious that a comparatively large amount of fluid will be displaced into the outlet pipe 26 under a comparatively lovt pressure. As pointed out above, this low pressure is due to the fact that the cross-sectional area of the piston I5 is comparatively large. A suitable cushion 52 (Figure 2) may, if desired, be located in the lower end of the cylinder l0 to cushion the strokeof the large piston. This cushion will, of course, be provided with an axial opening 52' through which the smaller piston, when independently operated, may pass.

Continued reciprocation of the two pistons as a unit will, of course, build up the pressure in the outlet lines 26 and when this pressure builds up to a point where it is equal to the force exerted downwardly by the piston l5 then this pressure will be sufficient to overcome the pressure of the spring 43 on the valve stem 42 which is holding the valve 40 closed. Therefore, when the equalization of pressure occurs, the valve 40 will be raised to permit the fluid within the lower. end of the cylinder and under the pressure which the large piston |5 has built up, to escape through the line 4| and back into the inlet line 24. When the valve stem 42 is lifted due to the opening of the valve 46, the rod 44 which is located in the vertical groove 45 in the side of the cylinder It] will, of course, be raised. The raising or lifting of the rod 44 will disengage the lug 31 at its upper end from the recess or notch 48 in the ring 46 which surrounds the cylinder l0. As soon as the lug 4! is disengaged from said notch, the coil spring 49 will immediately rotate the ring 46. Rotation of the ring 46 will cause the rod 50 which is secured thereto to engage the radially extended handle 5| on the flange l5 of the piston l5, whereby the piston |5 is rotated in'a clockwise direction. As explained above, this'rotation will cause the flange N5 of the piston to engage the notches 31 in the vertical arm 36 to lock the piston in its lowermost position. At the same time the pins 32 are disengaged from the horizontal leg of the slots 33 which disengages the inner piston 20 from the outer piston I5, thereby permitting said inner piston to be operated independently'of the large piston.

I Thus it will be seen that when the pressure built up by the operation of the piston l5 equals the force which is exerted by said piston, then the piston is locked in a lowermost position and the smaller piston 20. is disconnected from the large piston to permit independent operation of said smaller piston. Due to the small crosssectional area of the piston 20 operating within the axial bore I! of the large piston, it will be obvious that continued actuation or swinging of the maximum pressure of which it is capable, then the smaller piston 20 is automatically disconnected from the larger piston and is operated independently to displace a less amount of fluid under a higher pressure to the particular mechanism. Therefore in utilizing the pump to actuate a ram, it will be seen that upon initial actuation or at the start of the movement of the ram, there is practically no load or a very light sad on said ram. In such case it is desirable to displace a comparatively large amount of fluid so as to bring about an increased movement of the ram to bring it into actual working position.

Since the load on the ram is light at the start cessity for high pressure then the smaller piston is brought into-play and through the actuation or reciprocation of said smaller piston the fluid is forced to'the ram under a comparatively high pressure. Although the smaller piston is capable of placing a higher pressure on the fluid, it is pointed out that due to its small cross-sectional area it cannot displace as large amount of fluid as the larger piston l5. 'However, the displacement of a large amount of fluid at this time is unnecessary because the ram is already in its working position and a load is imposed thereon which requires a high pressure on the fluid.

The release of the large piston, after it has beenlocked in its lowermost position and its connection to the smaller piston 20 after having been disconnected, is easily accomplished by merely grasping the handle 5! on the flange N5 of the large piston 15 and rotating said piston in a counter-clockwise direction. This returns the parts to their normal position, the lug 41 cylinder for displacing the fluid therefrom under a low pressure, a second piston smaller than the first piston for displacing the fluid from the cylinder under a high pressure, said pistons being rotatable in said cylinder means for connect-. ing the'pistons whereby they move as a single unit until the pressure built up by the movement of the first piston is equal to the force exerted by that piston after which time the second piston is actuated, a spring element for urging said pistons rotatably in one direction, pressure controlled latch means for releasably holding said pistons against such spring urged rotation and a single means for moving the pistons.

2. A hydraulic pump including, a cylinder having fluid therein, a piston slidable in said cylinder and having an axial opening therethrough, a second piston slidable within the opening of the first piston, means for connecting the piston whereby both pistons move simultaneously and act as a large piston until such time as suflicient pressure of the fluid has been built up to equal the force exerted by said large piston, means for disconnecting the pistons whereby the second piston may be operated independently of the first piston after such equalization occurs, thereby first displacing a comparatively large amount of fluid from the cylinder under a low pressure and then displacing a comparatively small amount of fluid. under a high pressure, means for locking the first piston in its lowermost position when the second piston is disconnected therefrom, and means actuated by the pressure of the fluid for simultaneously operating the disconnecting means and the locking means.

3. A hydraulic pump including, a cylinder having fluid therein, a piston slidable in said cylinder and having an axial opening therethrough, a second piston slidable within the opening of the first piston, means for connecting the pistons whereby both pistons move simultaneously and act as a single large piston until such time as the fluid pressure built up by said piston equals the force exerted by thepiston, and means actuated by the fluid pressure for disconnecting the piston and locking the first piston in an inactive position, whereby the second piston may then be operated independently to displace a comparatively small amount of fluid under a high pressure.

4. A hydraulic pump including, a cylinder having fluid therein, a piston slidable in said cylinder and having an axial opening therethrough, a second piston slidable within the opening of the first piston, means for connecting the pistons whereby both pistons move simultaneously and act as at single large piston until such time as the fluid pressure built up by said piston 'equals the force exerted/by the piston, meanscomparatively small amount of fluid under ahigh pressure, and a single means for moving the pistons.

ROBERT E. MCGEE. 

